Combustion assessment of an ethanol/gasoline flex-fuel engine

Abstract

fuels in the world, and the research about the utilization of primary alcohols as spark ignition engine fuels proved interesting as a complement or substitute for gasoline automotive engines. The use of ethanol as an automotive fuel has been known in former times, indeed it was not widely used due to the high production costs of this alcohol in several countries. At that time, the technology of ethanol drawn from sugarcane was well known in Brazil and the Federal Government decided to create the National Ethanol Program (PROALCOOL) in order to encourage the research of ethanol as an automotive fuel. Industry and University started to develop technologies for that. In Brazil, the use of ethanol-powered vehicles has reached its peak in the eighties, but a standing point occurred in the last decade of the twentieth century. Due the market opening which took place in Brazil at the beginning of 90s, a large number of foreign petrol cars started to be sold in the country. At the beginning of the current century, Brazil witnessed the coming of the flex-fuel engine technology. The fuel-flexible engines may operate with 100 % of gasohol (an of-the-shelf blend of 18-25 % of anhydrous ethanol on gasoline in volume), 100 % of hydrous ethanol, or any blend of these fuels. Several investigations of performance, combustion, and emissions have been performed in the last years in order to assess the behavior of both engine and fuel blends in fuelflex engines and for pure petrol-designed engines. Reference [1] studied a four-cylinder, four-stroke, 8-valve flexfuel engine. The authors carried out the tests using a 78 % gasoline-22 % ethanol blend and commercial hydrous ethanol. The experiments were performed according to NBR-ISO 1585 standard under steady state starting from 6500 down to 1500 rpm in steps of 250 rpm. The measured power was corrected according to the standard. Ignition time and lambda were optimized in order to obtain the best Abstract This work surveyed the combustion behavior of commercial gasoline and hydrous ethanol on a flex-fuel Ford Rocam, four-stroke, four-cylinder, and 1000 cc, spark ignition engine. The crankshaft revolutions were varied and the emissions of oxygen, carbon dioxide, carbon monoxide, and unburned hydrocarbons were acquired. Also the mass fuel flow rate, the cooling fluid temperature, and lambda were measured in order to perform the assessment. Oxygen emissions were used to confirm lambda parameter measurement. Emission index values for carbon monoxide and unburned hydrocarbons were defined in order to compute the combustion efficiency. Nitrous oxides were related to the cooling fluid temperature. As expected, fuel consumption is greater for ethanol than for gasoline. Combustion efficiency which was higher for ethanol and nitrous oxide emissions presented lower values when the engine was operated with gasoline.

Critical review on recent progress of ethanol fuelled flex‐fuel engine characteristics

“…This is attributed to variations in ignition timing and water content between anhydrous and hydrous ethanol 90 . Likewise, combustion efficiency (CE) is slightly better for ethanol blends than gasoline in FFE due to the enhanced combustion process 91 …”

“…Also, the clean‐burning characteristics, lower carbon content, and oxygen presence in ethanol blends lead to increase CO 2 emission and reduction of HC and CO emissions in the exhaust. However, the difference in HC and CO emission values for ethanol blends and gasoline mode is minimum at lower speeds and loads due to the poor quality of the air‐fuel mixture 91 . However, NO X emission increases with the increase of ethanol share as compared to gasoline in FFE, because the faster flame propagation of ethanol and advancing the spark timing to obtain maximum power leads to an increase in combustion temperature 92 .…”

The misleading total replacement of internal combustion engines by electric motors and a study of the Brazilian ethanol importance for the sustainable future of mobility: a review

“…Oil reserves are finite and will need a replacement in a not so far future. Moreover, the combustion of gasoline and diesel releases to the atmosphere a considerable amount of pollutant gases [29][30][31][32], among them the CO 2 , and the reduction of their levels in the atmosphere is vital for the healthy future of humanity [33,34].…”

An evaluation of combustion aspects with different compression ratios, fuel types and injection systems in a single-cylinder research engine

“…In recent years, ethanol has been considered a promising alternative fuel to Brazil, the second-largest producer of this biofuel in the world [1]. The growing commercialization of flex-fuel vehicles, which can operate with any proportion ratio of ethanol and gasoline [2], combined with the favorable climate for the cultivation of sugar cane, the main source of the biofuel extraction in the country, and the mandatory 27% blend in gasoline are the major reasons for the ethanol success in Brazil [3][4][5]. Besides, the country's already existing experience with the fuel production and distribution is notable, once the Brazilian sugar ethanol industry dates back to 1970 due to the pro-alcohol initiative, which was an ethanol incentive program in the market that emerged after the 1970s oil crisis [1,6].…”